Newborn Physiologic Adjustments (Hematopoietic System)

Question 1

Why does the fetus need more RBC than an adult?

Answer 1

B/c fetal circulation is less efficient at oxygen exchange than the lungs.

Question 2

How long does it take for the RBCs, hemoglobin, and hematocrit levels to start normalizing?

Answer 2

They fall slowly over the first month.

Question 3

At birth the RBC ranges form?

Answer 3

4.6 to 5.2 million/mm cubed

Question 4

The term newborn can have a hemoglobin concentration of?

Answer 4

13 to 20.1 g/dL at birth.

Question 5

During the first 2 week hemoglobin concentration decreases gradually to..

Answer 5

12 to 20 g/dL

Question 6

Hematocrit levels at birth range from..

Answer 6

51% to 56% increasing slightly in the first few hours or days as fluid shifts from intravascular to interstitial spaces.

Question 7

By 8 wks hematocrit ranges are?

Answer 7

39% to 59%

Question 8

What is polycythemia defined as?

Answer 8

Central venous hematocrit grater than 65%

Question 9

What can cause polycythemia?

Answer 9

1. Delayed cord clamping
2. Maternal hypertension or diabetes
3. Intrauterine growth restrictions

Question 10

What are a significant factors in the levels of RBCs, hemoglobin, hematocrit?

Answer 10

Source of the sample.

Timing of blood sample

Question 11

Why is the source of the sample a significant factor in CBC levels?

Answer 11

B/c capillary blood yields higher values than venous blood.

Question 12

Why is the timing of the blood sample significant?

Answer 12

The slight rise in RBCs ager birth is followed by a substantial drop.

Question 13

What is the average of fetal hemoglobin in the infant’s blood at birth?

Answer 13

70%

Question 14

Why does the infant’s hemoglobin levels drop dramatical after birth?

Answer 14

B/c fetal hemoglobin has a short life span.

Question 15

What does the percentage of fetal hemoglobin fall to by 5 wks?

Answer 15

55%

Question 16

What does the percentage of fetal hemoglobin fall to by 20 wks?

Answer 16

5%

Question 17

Iron stores generally are sufficient to sustain normal RBC production for how long?

Answer 17

4 to 5 months in term infant, at which time a transient physiologic anemia can occur.

Question 18

What is the normal WBC in term newborns?

Answer 18

Approximately 18,000/mm cubed (range 9,000 to 30,000) is normal at birth.

Question 19

What does the WBC count increase to during the first day after birth?

Answer 19

Increases to 23,000 to 24,000.

Question 20

What WBC is normally maintained during the neonatal period?

Answer 20

12,000

Question 21

Why is serious infect not tolerated well by newborns?

Answer 21

Leukocytes are slow to recognize foreign protein and localize and fight infection early in life.

Question 22

What is the normal platelet range for term infants?

Answer 22

150,000 - 300,000.

Question 23

Can newborns synthesize vitamin K?

Answer 23

No, however, unless the K deficiency is great, clotting is sufficient to prevent hemorrhage.